google-api-translate-java now supports Version 2 of the API,this requires using an API key. refer http://code.google.com/p/google-api-translate-java/.
Google Translate API v2 is now available as a paid service only, and the number of requests your application can make per day is limited. Refer http://code.google.com/apis/language/translate/v2/getting_started.html.
google-api-translate-java is a Google Code project enables using Google Translate from a Java application, to provides a simple, unofficial, Java client API for using Google Translate.
In order to include google-api-translate-java application, you have to download the jar, save to any location in your local had disk. In my case, it's /google-api-translate-java-0.82.jar in my home folder.
In Eclipse, Right click your project>Properties>>Java Build Path, and click Add External JARs, browse to include the downloaded jar file in your path.
I have a simple Android exercise, AndroidTranslate, using google-api-translate-java to involve Google Translate.